JPH0736344Y2 - Color liquid crystal panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a liquid crystal panel structure for multicolor or natural color display.

[Background of the invention]

In recent years, with the development of various information devices represented by computers and televisions, the role of the display device as an output terminal of the information has become more and more important. Conventionally, a CRT (cathode ray tube) has been most widely used as this display device, but in recent years, the ratio occupied by an LCD (liquid crystal display device) has rapidly expanded due to its thinness and low power consumption. On the other hand, it is needless to say that the color display is generally preferable because the display device has a characteristic of appealing to human eyes. Therefore, the need for color LCDs has become extremely large.

[Conventional technology and its problems]

Various ideas have been made to realize a color LCD. It is, for example, an ECB (electrically controlled birefringence) method, a guest host method, a birefringent film-TN (twisted nematic) method, an optical rotatory dispersion-cholesteric method, etc., but in terms of natural color displayability and structural reliability, A color LCD that uses liquid crystal as an optical shutter and combines it with three primary color filters of red (R), green (G), and blue (B) is most effective.

There are various configuration methods to combine the liquid crystal panel and the color filter, but realizes high-density and high-definition display,
Moreover, in order to prevent the performance of the liquid crystal itself as an optical shutter from being deteriorated by the introduction of the color filter, the configuration as shown in FIG. 3 is preferable. In this case, the color filter 23 is provided adjacent to the liquid crystal 24, and the transparent electrode 31 on the color filter 23 side is formed on the color filter 23. As a result, the liquid crystal shutters that actually operate in matrix form as individual small pixels and the three liquid crystal shutters formed at the positions corresponding to the individual liquid crystal shutters.
There is no displacement when the screen is viewed obliquely with respect to the relative position of the primary color to the normal mosaic color filter. Further, since the liquid crystal 24 is driven between the transparent electrodes 31 and 32 without interposing the color filter 23, the characteristics of the liquid crystal as an optical shutter can be maximized.

The structure shown in FIG. 3 is a standard structure in a thin film transistor (TFT) type active matrix type color LCD (see, for example, Nikkei Electronics, P. 211, No. 351 (1984)). Since it is general that no active element is arranged on the side of the substrate on which the color filter is formed, there is a great advantage that the transparent electrode 31 on the side of the color filter 23 does not require solid patterning on the entire surface.
Therefore, there are very few restrictions on the film quality, resistance value, etc. of the transparent electrode, and there is no serious technical problem.

On the other hand, the structure shown in FIG. 3 has a simple matrix type color LCD.
However, there are various difficulties that cannot be compared with the active matrix method. It can be said that the resistance value of the transparent electrode and its patterning property are particularly important issues. That is, in the case of the simple matrix method, it is necessary to form a substantially stripe-shaped fine pattern in the color filter portion, and further, the resistance value thereof is not reduced to tens of Ω or less in area resistance value to obtain sufficient image quality. However, in the structure shown in FIG. 3, since a dye-type color filter with an acid dye is generally present when forming a transparent electrode, the color filter has a heat resistance and a chemical resistance, so that it cannot be used at a low temperature. Formation of transparent electrodes and patterning under mild conditions are required, and as a result, it is extremely difficult to satisfy the required specifications as a color LCD substrate.

Although the above problem is limited to the simple matrix method, the same discussion applies to the two-terminal active matrix method. This two-terminal type is a MIM (Metal-Insulat
or-Metal) or DR (Diode-Ring), which is different from the three-terminal TFT described above, and requires patterning of the transparent conductive film on the color filter side substrate, and the required performance is It is almost equivalent to the simple matrix method.

Now, as to the problem of the patterning property involved in the formation of the transparent electrode, it is extremely necessary to provide an inorganic transparent thin film between the color filter and the transparent electrode as shown in, for example, JP-A-62-153826. Proved to be effective. FIGS. 4 and 5 are cross-sectional views of such a structure. FIG. 4 shows a case where an inorganic transparent thin film 52 is further formed directly on the color filter 23, and then a transparent electrode 31 is formed. In FIG. 5, the organic transparent thin film 51 is formed on the color filter 23, and then the inorganic transparent thin film 52 and the transparent electrode 31 are formed. By the way, as an embodiment in the above-mentioned JP-A-62-153826, a structure similar to that shown in FIG. 5 is described. As the organic transparent thin film 51, a 1 μm thick polyimide film and as the inorganic transparent thin film 52 are used. A 100 nm thick SiO ₂ film is used. However, as a result of an experiment conducted by the present inventor, when the ITO (indium tin oxide) film, which is a transparent electrode, was etched with a hydrochloric acid-based solution using the above-mentioned thin SiO ₂ film, fine etching was performed during the resist stripping process. Since the transparent electrode pattern was frequently peeled off, the result was inevitable.

[Purpose of device]

The present invention is intended to solve a serious defect in the patterning process by etching the transparent electrode formed on the color filter, and as a result, it has good image quality and high reliability, and is economical. It is an object of the present invention to provide an ideal color liquid crystal panel that also has properties.

[Means for Solving the Problems]

The configuration of the present invention is a color liquid crystal panel in which an inorganic transparent thin film is formed directly on a color filter or through an organic transparent thin film and a transparent electrode is formed on the inorganic transparent thin film as a component of the liquid crystal panel. In the above, by making the inorganic transparent thin film an island-shaped incomplete thin film, the etching pattern of the transparent electrode can be made extremely excellent.

〔Example〕

FIG. 1 shows a sectional view of a color liquid crystal panel according to the present invention. Although only one of the two transparent substrates constituting the liquid crystal panel is shown here, the other transparent substrate is the one used in a normal simple matrix drive liquid crystal panel,
That is, a transparent electrode is formed on a glass substrate. However, another structure of the other transparent substrate is one for active matrix driving in which two-terminal active elements such as diodes or three-terminal active elements such as thin film transistors are regularly arranged on a transparent substrate such as glass. Is also included.

In this embodiment, first, the color filter 23 is formed on the transparent glass plate 21. Glass is usually used as the transparent glass plate 21, and its surface is coated with silicon oxide as needed. As the color filter 23, there are a color filter dyeing a gelatin thin film, a spinner coating type dyeing resin color filter, a pigment vapor deposition type filter and a printing method filter, each of which has its advantages and disadvantages. In this embodiment, the color filter by the pigment-based printing method is used, but other kinds of color filters described above can also be used. The pattern of the color filter 23 has a stripe shape, a mosaic shape, or the like, which are used properly according to the purpose. Then, the organic transparent thin film 51 is formed by covering the color filter 23, and the inorganic transparent thin film 52 is formed by further covering the organic transparent thin film 51.

Here, the organic transparent thin film 51 has two major functions of flattening the irregularities on the surface of the underlying color filter 23 and at the same time reinforcing the strength of the color filter 23. In addition, the organic transparent thin film 51 is a color filter 23.
It may also act as a barrier against the outflow of mainly ionic impurities contained in the liquid crystal layer, which is also important in this sense. A polymer resin is preferable as a substance satisfying these required functions, and the planarization effect is particularly remarkable due to its thixotropic property. Further, from the viewpoint of strength, hardness is an important factor, and acrylic resin or silicone resin can be said to be preferable. Since it is formed in a heated state, strength in a heated state is also important. From this point of view, a resin having high heat resistance is preferable, and a polyimide- or polyamide-based resin is optimal when the film-forming property and the like are taken into consideration. The thickness of the organic transparent thin film 51 that best exhibits its function is 0.5 μm to 2 μm. In this embodiment, a 1.2 μm thick polyimide film is used.

The present invention is concerned with the following inorganic transparent thin film 52, which is formed in an island shape as shown in the figure.
The underlying organic transparent thin film 51 is partially exposed on the surface after formation. Of course, the formation of such thin islands strongly depends on the film forming method, but generally, if a thin film of about 10 nm is formed, the island-shaped inorganic transparent thin film 52 of the present invention can be obtained. Vapor deposition, sputtering, CVD (chemical vapor deposition), etc. are often used as the film forming method, and silicon oxide,
Silicon nitride, aluminum oxide, tantalum pentoxide and the like have preferable characteristics. Many studies have been carried out on the island-like growth of thin films, and 10 nm to 10
An island structure of about 0 nm is observed by an electron microscope. In this example, a silicon oxide film having a thickness of about 12 nm was formed by a sputtering method, and an island structure having a thickness of about 50 nm was confirmed. still,
It was in the system of this example that such an island structure was effectively observed in the range of 4 nm to 25 nm in the film thickness of silicon oxide.

Next, ITO was used as the transparent electrode 31 by sputtering to a thickness of about 300 nm.
After forming the film of (1), an approximately striped shape was obtained by an etching process using a hydrochloric acid-based solution. The pattern of the obtained electrode was extremely good, without overetching and of course no missing of a fine pattern. The reason why such good patterning has become possible is the effect of the island-shaped inorganic transparent thin film 52 of the present invention, and the mechanism is considered as follows. That is, the patterning process consists of etching with an acid solution to form a transparent electrode and removing the resist with an alkaline solution to remove the resist. The thin film 52 and the transparent electrode 31 are excellent, and the organic transparent thin film 51 and the transparent electrode 31 are superior to the latter. Therefore, the island thin film capable of providing two kinds of finely mixed surfaces as in the present invention is effective for improving the etching process including the two steps. In the island-shaped grown inorganic transparent thin film, the surface between the islands does not necessarily need to be exposed in the complete sense, and the surface of the organic transparent thin film is not necessarily exposed. Even if the ITO film is formed next time, there is no problem as long as the organic transparent thin film and the ITO are substantially bonded to each other.

After this, a normal orientation treatment is performed, and a glass substrate prepared separately is overlaid to form a panel. In this way, a color LCD having the structure shown in FIG. 3 is obtained, but with respect to the step of forming the panel, the same handling as that of the conventional liquid crystal panel is sufficient.

FIG. 2 shows another embodiment of the present invention. Compared with FIG. 1, the feature here is that the organic transparent thin film 51 is not provided.
If the color filter 23 also has the function of the organic transparent thin film 51 as described above, this structure is sufficient, and this is sufficient in the case of a spinner coating type color filter using a heat resistant resin.

[Effect of device]

As described above, according to the present invention, a color LCD having an excellent display performance can be easily produced, and it is very effective in terms of yield and cost and mass productivity.

In particular, the patterning process of the transparent electrode, which has been a problem in yield, is dramatically stabilized.

[Brief description of drawings]

1 and 2 both relate to the present invention. FIG. 1 is a sectional view showing a color liquid crystal panel showing a first embodiment, and FIG. 2 is a sectional view showing a color liquid crystal panel according to a second embodiment. 3 and 4 are sectional views showing the basic structure of a color liquid crystal panel, and FIGS. 4 and 5 are sectional views showing a conventional color liquid crystal panel. 23 …… Color filter, 31 …… Transparent electrode, 51 …… Organic transparent thin film, 52 …… Inorganic transparent thin film.

Claims (3)

[Scope of utility model registration request] 1. A liquid crystal comprising a color filter formed on a glass plate, an inorganic transparent thin film formed at least on the color filter, and a large number of transparent electrodes formed on the inorganic transparent thin film and having a substantially stripe shape. A color liquid crystal panel as one component of a panel, wherein the inorganic transparent thin film is an island-shaped incomplete thin film. 2. A color filter formed on a glass plate, an organic transparent thin film formed by coating the color filter, an inorganic transparent thin film formed on at least the organic transparent thin film, and formed on the inorganic transparent thin film. In a color liquid crystal panel having a large number of transparent electrodes each having a substantially stripe shape as one component of the liquid crystal panel, the inorganic transparent thin film is an island-shaped incomplete thin film. panel. 3. The color liquid crystal panel according to claim 1, wherein the inorganic transparent thin film is silicon oxide.